This invention relates generally to a liquid crystal display device of the matrix type and more particularly to a liquid crystal matrix display wherein the driving duty cycle is increased and the driving voltage is reduced when scanning electrodes are simultaneously driven as compared to the condition where scanning electrodes are independently driven. In recent years, liquid crystal display devices have been used in many types of apparatus, such as watches, clock radios, electronic calculators and the like because a liquid crystal display has the characteristics of consuming low power as compared to other types of display devices. Because this equipment, that is, watches, radios, calculators, etc. are in many instances multifunctional, it is necessary to provide a display panel on which many different kinds of information and data are to be displayed. For this reason, matrix display panels have come into common usage. In a matrix display device, information is displayed using picture elements which are formed at locations at which a plurality of scanning electrodes which are parallel one with the other, cross a plurality of signal electrodes which are parallel one with the other. Overlapped portions of the intersecting electrodes can be displayed when driven. Herein, in the conventional manner of the industry, electrodes which are oriented in a lateral direction on the display are called scanning electrodes, and those electrodes which are oriented in the lengthwise direction of the display are called signal electrodes.
As stated above, it is possible to display various types of data and information on a liquid crystal matrix display device. However, in a liquid crystal display device, because only the overlapped portions can be visibly displayed, there are portions of the electrodes which are never displayed, or in other words, electrodes are present in portions of the display where no information is ever visibly displayed. Accordingly, the total area of electrodes is larger in a matrix display as compared with a display which uses seven segments, each segment devoted to forming the portion of an alpha-numeric character. Thus, power required for charging and discharging the capacitance between the scanning and signal electrodes is greater in the matrix device as compared to a segmented device. When a conventional liquid crystal matrix display device is used in a digital wristwatch or similar battery operated device, there is the problem that battery life is short.
What is needed is a liquid crystal matrix display which consumes little power and provides a high quality presentation.